There are tons of free data sources for your real estate web site and I have one more to add to my list — Walk Score. If you’re not familiar with Walk Score, this is their description of how it works:

Walk Score helps people find walkable places to live. Walk Score calculates the walkability of an address by locating nearby stores, restaurants, schools, parks, etc. Walk Score measures how easy it is to live a car-lite lifestyle—not how pretty the area is for walking.

Walk Score now has two integration options to bring Walk Scores directly into your site — an API that returns a Walk Score for any lat/long point or a real estate tile, which is a pre-built widget that displays a Walk Score using an address as the input. Both integration options are worth taking a look at depending on whether a) integration flexibility & control or b) ease of technical integration is more important to you.

ZipRealty recently added Walk Score information into the neighborhood info tab of their listing detail pages using the tile module. Here’s an example (you’ll have to login to ZipRealty). Another example of the tile integration is Dwellicious (in the Walk Score tab), which I found via Dan’s comment on 1000Watt.

Particularly for those who focus on green housing, integrating Walk Scores could be a great addition to your web site given your target clientele. To me, the fact that there are 1,600 installs of their basic widget is proof of a strong appetite for walkability data in the real estate space.